(10-26) 12:43 PDT OAKLAND -- More than 150 Occupy Oakland activists gathered downtown Thursday to mark the anniversary of the dismantlement of their encampment with chalk drawings, speeches and an evening march, and though anger flared at times they managed to maintain a basic harmony between those calling for peace and those who don't mind violence.

Several, particularly those wearing Black Bloc-style dark clothing and masks, said they would defy police by camping overnight in front of City Hall, but that didn't happen.

City officials had said nobody would be allowed to camp in Frank Ogawa Plaza, the spread of brick, concrete and grass in front of Oakland City Hall.

Vet tries to keep group going

One year ago Thursday, police cleared the Occupy Oakland encampment of about 150 tents in the plaza and a tear-gas-filled riot followed, resulting in injuries and international headlines.

The person most seriously injured in that riot - Iraq war veteran Scott Olsen, who was hit in the head by a projectile beanbag - was in front of City Hall again Thursday, saying he wanted to help keep the Occupy movement going and that he intended to camp out in the plaza.

Plans for Thursday had been colored by a deepening division between two ideologies in the Occupy movement, which has from its beginning been leaderless by design.

On one side are moderates who say they are fed up by window-smashing and other violence that erupted at several protests over the past year. They say they want Occupy's message to go back to its original focus on economic inequities.

On the other side are anarchists who consider police and much of government corrupt and like using a "diversity of tactics," which means they consider violence a viable form of protest.

The moderates outnumbered the extremists throughout the day.

Ron Streitz, 64, of Oakland said the mood at the gathering reminded him of the Occupy movement when it began in early October 2011 and included a wide range of people, from office workers to college students and the homeless. That was before moderate voices were marginalized.

"I think that was the intention - to have a gathering that is true to the spirit of Occupy," Streitz said.

About 20 people dressed as Black Blockers and carrying homemade shields said if any violence erupted, it would be the fault of the police.

"I hope the police will let us be peaceful," said one young man wearing a bandanna, standing next to a similarly garbed friend who carried a shield bearing the letters "FTP," meaning "F- the Police." Like most Black Blockers, he would not give his name.

At 7 p.m., the crowd set off on a two-hour march throughout downtown, stopping briefly at police headquarters at Eighth and Washington streets. There, marcher Dina Cook, 37, of Oakland challenged others to stop shouting angrily at police. She was surrounded by about a half dozen protesters who screamed at her to "Shut up, bitch." Other demonstrators separated them.

"I am trying to represent a peaceful movement, and I'm not scared to tell these people who aren't even from here to stop messing with the cops," Cook said shortly afterward. "They don't represent our group. They're just trying to get on TV."

Man arrested for rocks

At least 200 police remained alongside the crowd throughout the evening as the march ended up back at the plaza, and then dissipated by Friday morning. Although authorities said two men were arrested - one on suspicion of hitting an officer with a rock and another for allegedly obstructing an officer and possessing drugs - there was there were no physical confrontations with police.

"We tried to facilitate this march throughout the downtown area," said Assistant Chief Anthony Toribio.